Firstly,
why would you come off as a womanizer if you ask a girl out?
Is every guy who ever asked a girl out a womanizer?
Theres nothing wrong with being social and also theres nothing wrong about wanting to have sex with women.
There's three types of approaches you can do
Direct
Indirect
Situational
Direct
Go up to a girl and tell her she's cute/beautiful/gorgeous etc. (but not something like 'hot sexy peice of ass'

)
eg. "Hey <pause & look into her eyes>, I saw you from over there and thought you where gorgeous so i thought i should come and say hi!"
This is a win win... as you will have approached her and got over your anxiety and it will brighten up her day (and ego) that a guy thought that they were gorgeous, even if she does tell you to f-k off. Also she will know your intentions right from the get go, so she won't have to wonder 'why is this guy talking to me'
Make sure you pause and look in to their eyes, this will make sure she has all of her attention on you and not what she was doin.Indirect
Ask a random question
eg. The olde opinion opener xD
''Hey, <pause & look into her eyes> can i ask a females opinion on something''
''Do you like it when guys approach direct or indirect?'' <= Anything where you ACTUALLY want their opinion
Situational
Look at something she is doing or wearing... reading a book, a cool necklace, crossing the road etc
and make a statement about it or ask a question about it
If all goes well, ask her to give you her number then take it from there.
Good luck! it took me 2 months to make my first approach, but you will relise that people are very responsive and open when you start, and it is very easy!
ps.
I suggest if you want to get good at this stuff, google pick-up-artist, read 'the game' - Neil Strauss and get a copy of 'Double your dating' by David DeAngelo.